Inertia operated hermetically sealed switch



4 Jail 24, r 1967 w. T. WAKELY 3,300,603

INERTIA OPERATED HERMETICALLY SEALED SWITCH Filed Nov. 23, 1964 fg. 1. 'ry 2.

X X X X ,Z6 ffl' 24 QW .24 ll'l 3,2 IH 26 `20 Z0` gall Imi/ela tof; W'Zba Thomas W'eZ United States Patent Oilce 3,300,603 INERTIA OPERATED HETICALLY SEALED SWITCH Wilbur T. Wakely, Dallas, Tex., assignor to Texas Instruments Incorporated, Dallas, rlex., a corporation of Delaware Filed Nov. 23, 1964, Ser. No. 413,089 1 Claim. (Cl. 20G-61.45)

This invention relates to switches and particularly to -an electric switch used to open or close an electric cir- -cuit and operated by inertia, centrifugal or magnetic force.

It is an object of the invention to provide an improved switch which is actuated by centrifugal force, magnetic force, acceleration or deceleration.

It is another `object to provide an improved switch mechanism of the type described which can readily be miniaturized.

Another object is to provide a switch of the type described which is of xed calibration.

Another object is to provide a switch of the type described which is hermetically sealed.

Another object is to provide a switch mechanism of the type described which is of a relatively simple construction and is inexpensive to make.

Another object is to provide a switch which is capable of withstanding high loading forces.

It is yet `another object to provide an improved switch mechanism capable of being used in conjunction with an automobile transmission and responsive to centrifugal force.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illustrated:

FIG. l is a longitudinal sectional view of the switch in open circuit position; and

FIG. 2 is a view similar to FIG. l but in a closed circuit position.

Dimensions of certain of the parts as shown in the drawings may have been modified and/or exaggerated for the purposes of clarity in illustration.

In the illustrated embodiment lof the invention, the switch 10 comprises a housing 12 made of an electrically conducting metal which mounts leads 14 and 16 of a circuit to be controlled by the switch. The circuit iS not shown since it does not form a part of the invention. The housing 12 is cup-shaped with a closed end 18 and a cylindrical shell 20 depending therefrom. Lead 14 is attached, as by welding, to end 18 at 22. The housing 12 forms a chamber 24 in which is slidably received a mass 26 which is attached to guide member 28. Guide 4member 28 may be rounded at 30 t-o facilitate sliding of guide 28 and mass 26 along the Z-Z axis of the cylindrical shell 20. The member 28 may be formed of the same material as mass 26 or it may be formed from a material of low friction characteristics, such as an oil impregnated metal or in some instance where it is desired further to electrically insulate the guide a plastic material of low friction characteristics such as a polytetrauoroethylene (Teflon), can be utilized. The mass 26 is turned down to form a shoulder 32 which serves as a seat for a spring 34 which is formed of an electrically conductive material and will be further described below. Housing 12 is closed by a conventional header 3,300,603 Patented Jan. 24, 1987 subassembly 36 shaped complimentary to shell 20 to lit closely therewithin and `consists of a generally cylindrically shaped frame 38 which houses glass insulation 41 and lead 16. One end of frame 38 is turned inwardly at 40 to provide an electric connection between frame 38 and spring 34 as described below; the other end of frame 38 is bent outwardly to form a flange 42 which mates with flange 44 similarly formed in shell 20. Mating flanges 42 and 44 are attached as by welding at 46 around the periphery of the flanges to form an air-tight seal. Lead 16 is mounted in header 36 by means of glass 41 which electrically isolates the lead from frame 38 and forms a hermetic seal therewith. Spring 34 extends from shoulder or seat 32 t-o portion 40 of frame 38 and serves to bias mass 26 and guide 28 away from header 36.

The circuit of the switch may be traced in FIG. 2 from lead 14 to housing 12, frame 38, spring 34, mass 26 to lead 16. The parts forming the circuit are all made of electrically conductive material.

The operation of the device will now be described. Anyone of three forces can be utilized to move the mass 26 from the contacts open position shown in FIG. l to the contacts closed position shown in FIG, 2. One such force is caused by inertia or acceleration/deceleration. If the device is accelerated by a predetermined amount along the Z-Z axis or an axis parallel to the Z-Z axis or an axis having a force component parallel to the Z-Z axis in the direction of arrow 50, the mass 26 will be urged due to inertia, against the bias of the spring, into a contacts making direction, whereby mass 26 contacts lead 16 at 48, which lead extends beyond the eyelet toward the mass as shown.

Conversely, if the device is decelerated in the opposite direction, i.e., in direction of arrow 60, the mass 26 will be urged in a contact making direction.

The second such force is centrifugal force. The device may be rotated about an X-X axis which will create centrifugal force acting upon mass 26 to urge the mass against the bias yof the spring in the direction of arrow 60. The X-X axis or an axis having a force component parallel to the X-X axis may be located anywhere above the center of gravity of conductive mass 26 as viewed in FIG. l within the purview of this invention.

Magnetic force may also be utilized to -actuate the switch. For this type of switch, the mass 26 would be constructed of a magnetic substance so that a predetermined magnetic force acting in a direction to cause the mass to move toward the lead 16 would effect contact closing.

The particular force necessary to cause the contacts to close or make in the rst two cases above is determined by the strength of the spring, th-e weight of the mass 26 and guide 28 and the friction between guide 28 and shell 20. The force in the third case would also be dependent upon the materials chosen for the elements, particularly the mass 26. Calibration then may be effected by varying any one of these factors during manuture. Once the parts are assembled, there are no adjustable parts to get out of adjustment. That is, the switch is of a fixed adjustment type and will therefore maintain the original calibrated conditions.

The time necessary for mass 26 to move from the position shown in FIG. 1 to the position shown in FIG. 2 is, of course, dependent inter alia, upon the clearance between guide 28 and shell 20. If it is desired to have a delay of a specied time in actuation of the switch, this could be effected by controlling the amount of pneumatic force which would oppose the movement of the mass. This force would be dependent on the amount of clearance between guide 28 and shell 20. The greater the clearance, the less the opposition to movement of guide 28. Further if desired, through openings or air passages (not shown) and also peripherally extending radial notches (not shown) could be provided in guide 28 to further reduce the pneumatic forces opposing movement of the mass 26. v

It should be noted that inherently the switch is insensitive to forces in directions other than downwardly along the Z--Z axis as seen in FIGS. 1 and 2. Y

The device has many uses, one of which is in conjunction with an automobile transmission. Switch 10 is mounted for rotation about the X-X axis shown in FIG. l so that when the motor reaches a predetermined number of revolutions per minute, switch 10 is actuated by centrifugal force causing mass 26 to contact lead 16 thereby closing a circuit which switches in an overdrive mechanism. This overdrive mechanism would continue operating as long as the motor rpm. stayed 'above the predetermined amount.

The invention permits a construction which is simple and rugged and can be made in miniature size without sacrificing reliability. As an example, the applicant makes one size approximately 1A cubic centimeter.

The resistance of the circuit may be lowered by gold plating the elements which form `a part of the Circuit described above.

It should be understood that it is within the purview vf the invention to provide switches that open, rather than close, in response to a predetermined force merely by biasing the mass 26 of spring 34 toward rather than away from lead 16.

It can be seen that the device illustrated is simple in construction, rugged, has only one moving part, is of fixed calibration, hermetically sealed and fulfills all of the objects mentioned at the beginning of the specifica- .tion besides other advantageous results.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

As many changes could be m-ade in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense, and it is also intended that the appended claim shall cover all such equivalent variations as come within the true spirit and scope of the invention,

I claim:

A normally open electric switch comprising:

(a) an electrically conductive cup-shaped housing having a closed end and an open end and forming a chamber therein;

(b) an outwardly radially extending annular flange formed on the open end;

(c) a header mounted in the open end having a frame with an outwardly, radially extending annular flange `on one end of the frame mating with the llange on the housing and hermetically connected thereto and `an inwardly extending annular ange formed on another end of the frame;

(d) two electrical leads;

`one lead electrically connected to the closed end of the housing, the other lead mounted in the header frame and electrically isolated therefrom;

(e) glass insulation mounting the other lead in the header and forming `a hermetic seal of the open end yof the housing;

(f) the other lead extending into the chamber slightly beyond the inwardly extending ange of the header frame;

(g) an electrically lconductive movable mass slidably mounted in the chamber adapted to move to and from the other lead and formed with an annular spring seating shoulder in alignment with the inwardly extending flange of the header frame;

(h) an electrically conductive spring contacting the inwardly extending ange of the header trarne and the annular spring seating shoulder of the mass and biasing the mass away from the other lead; and

(i) guide means attached to and guiding the mass means in the chamber during its movement to and from the `other lead;

whereby force of a predetermined magnitude to overcome the bias of the spring and acting in a direction urging the mass toward the other lead will cause the mass to contact the other lead closing a circuit from the one lead, through the housing, the frame, the spring, the mass to the other lead.

References Cited by the Examiner UNITED STATES PATENTS 2,982,829 5/1961 McCabe et al. 20G-61.45 X 3,038,973 6/ 1962 Alpert 200-61 X 3,141,936 7/1964 Boyle etal 20G-61.53 3,166,654 1/1965 Mitchell 200-112 BERNARD A. GILHEANY, Primary Examiner. ROBERT K. SCHAEFFER, Examiner, I. BAKER, Assistant Examiner, 

